Window vent visors

[wyatt]

Originally Posted by Daox

I'd have to disagree, I don't think its debatable.

#1) They increase frontal area which inherantly increases drag.

#2) There is no way they don't cause separation. Its an edge hanging out from the car a good inch. Without it, there is at least has a chance for the flow to stay attached.

And hence the debate

1)I am not arguing that they don't increase frontal area
2)I am not arguing that they don't cause separation... rather that they COULD keep air flow attached to the point that it's parallel with the car instead of it separating at an angle away from the car. IN THEORY this COULD reduce the Cd of the car. If they are completely contained in a region of separation they will have little or no effect. The only way they hurt the car's Cd would be if there is really no region of separation.

This being said, I would guess that if you were able to do coast down testing the Cd would not vary enough for you to notice.

[Sean T.]

I removed the rear ones because they are never used, and as far as I could tell they were only acting like parachutes.

As for the front, I was plowing down the freeway last weekend and I found that after reaching out and breaking the seal only on the backmost edge of the deflector (down the B-pillar) drastically reduced air noise. Think about it... they act like parachutes at the rear end also. Popping the back end loose lets the any air trapped in them flow right through.

[taco]

i have in channels on my 09. u cant see them fron the front. if they stick out 1/4 of an inch it would be alot. i dont think that style would hurt as much.

pic. click it they grey one.
http://www.customtacos.com/gallery2/...0/IMG_2667.JPG

also the whire one, has NOT been driven off-road. that is all 2 lanes paved roads to work and back.

[winkosmosis]

Maybe you should cut out the rear edge that acts like a parachute?

[chipX]

Originally Posted by sepp

ive been wondering about this to, but apparently they are only advertised as weather deflectors. and never for any aerodynamic gain, wich they certainly would do if there was any.

but i noticed that all modern trucks have these wind guides to the sides of their cabs, to help keep the airstream attached.



why not place such guides on all the edges of our cars where the airsteam detaches? like above the nose, above the windshield, around the A-beams... would that do any good?

Anyone with more info on the above, as i have bee looking at these lately

[aerohead]

My only thought is that during summer operation,the partially open windows might allow you to dispense with the air-conditioning,using fresh air and blower only, for a little savings.------------- For the rest of the year,the visors,as others have already mentioned,cost you in an increased drag penalty.Since they have not been included in the highest mpg cars offered,we can take that as a clue as to their value in an energy savings context.